<style>
body{font-size:14px;font-family:Microsoft Yahei,fantasy;margin:0;padding:0;line-height:1.414;}
a{text-decoration:none;}
*{margin:0;padding:0;box-sizing:border-box;}
header,footer,.main{width:960px;margin-left:auto;margin-right:auto;}
.main-top-nav{background-color:#e8f3ff;border-top:2px solid #b8e9ff;padding:6px 0;}
.main-content{display:flex;padding-top:15px;}
.s_left{width:200px;font-size:16px;}
p,ul,li{margin:0;padding:0;list-style:none;}
.s_main{width: 745px;margin-left:15px;}
.s_left>ul>li>a{height:30px;display:block;line-height:30px;padding-left:10px;border-left:4px solid #b1c9e4;background-color:#dae8f9;color:#313131;}
.s_left>ul>li + li{margin-top:7px;}
.s_main>h4{font-size:18px;border-bottom:1px solid #e8f3ff;}
.s_main .content{padding:20px 10px;}
.s_left>ul>li>a.active {background-color: #ffe860; border-color: #f3d41c; }

</style>
<script src="https://lib.baomitu.com/jquery/2.2.0/jquery.min.js"></script>
<script>
$(function(){
    var urlstr = location.href;
    var urlstatus=false;
      $(".s_left>ul>li>a").each(function () { 
            if ((urlstr).indexOf($(this).attr('href')) > -1 && $(this).attr('href')!='') {
             $(this).addClass('active'); 
             urlstatus = true;
            } else {
             $(this).removeClass('active');
            }
       });
    if (!urlstatus) {
        $(".s_left>ul>li>a").eq(0).addClass('active'); 
    }

})
</script>